Oblak Adrijana, Hribar Maša, Hristov Hristo, Gregorič Matej, Blaznik Urška, Osredkar Joško, Kušar Anita, Žmitek Katja, Lavriša Živa, Zaletel Tjaša, Krhin Blaž, Pravst Igor, Gaberšček Simona, Zaletel Katja
Division of Nuclear Medicine, University Medical Centre Ljubljana, Ljubljana, Slovenia.
Nutrition Institute, Ljubljana, Slovenia.
Eur J Clin Nutr. 2024 Dec;78(12):1105-1110. doi: 10.1038/s41430-024-01492-y. Epub 2024 Aug 8.
In population studies, iodine intake estimation relies on median urinary iodine concentration (UIC). However, interpreting UIC measurements can be challenging.
In our study, we included 772 adult participants from three groups: nationally representative gender-mixed, women of reproductive age, and pregnant women. We measured UIC and urinary creatinine (U-Cr) to calculate the iodine-to-creatinine ratio (I/Cr). U-Cr cut-off value of 0.226 g/L was used for differentiation between diluted and undiluted urine samples. After excluding samples below this cut-off, new median UIC and I/Cr ratios were calculated. We additionally evaluated the influence of urine sample collection time on UIC.
Median UICs were 91.8 µg/L for nationally representative group, 58.3 µg/L for women of reproductive age, and 74.9 µg/L for pregnant women, while I/Cr ratios were 91.7, 102.0, and 159.2 µg/g, respectively. After implementing U-Cr cut-off and excluding all data where U-Cr was below cut-off, new median values were 93.4, 76.3, and 95.4 µg/L for UICs, and 88.6, 88.8, and 128.7 µg/g for I/Cr ratios, respectively. In women of reproductive age, median UIC was significantly lower in urine samples collected after 9:30 and after 12:00 as compared to samples collected before 9.30 (53.4, 57.8, and 97.3 μg/L, respectively).
UIC results should be interpreted with caution, considering urine dilution and sample collection timing. U-Cr measurement should be included in population-based iodine intake studies, with corrections applied especially for pregnant women and younger adults, for whom morning is best for single-spot samples.
在人群研究中，碘摄入量的估计依赖于尿碘中位数浓度（UIC）。然而，解读UIC测量结果可能具有挑战性。
在我们的研究中，我们纳入了来自三组的772名成年参与者：具有全国代表性的性别混合组、育龄妇女组和孕妇组。我们测量了UIC和尿肌酐（U-Cr）以计算碘肌酐比值（I/Cr）。U-Cr截止值0.226 g/L用于区分稀释和未稀释的尿液样本。排除低于此截止值的样本后，计算新的UIC中位数和I/Cr比值。我们还评估了尿液样本采集时间对UIC的影响。
具有全国代表性的组UIC中位数为91.8 µg/L，育龄妇女为58.3 µg/L，孕妇为74.9 µg/L，而I/Cr比值分别为91.7、102.0和159.2 µg/g。实施U-Cr截止值并排除所有U-Cr低于截止值的数据后，UIC的新中位数分别为93.4、76.3和95.4 µg/L，I/Cr比值分别为88.6、88.8和128.7 µg/g。在育龄妇女中，9:30之后和12:00之后采集的尿液样本中的UIC中位数显著低于9:30之前采集的样本（分别为53.4、57.8和97.3 μg/L）。
考虑到尿液稀释和样本采集时间，应谨慎解读UIC结果。基于人群的碘摄入量研究应包括U-Cr测量，尤其要对孕妇和年轻人进行校正，对他们来说，晨尿是单点样本的最佳选择。
